Although methods for treating cancer include a surgical treatment, a radiation therapy and a chemotherapy, these treatments are accompanied by side effects, or the treatment is limited to apply according to the degree of progression of cancer. In particular, anti-cancer drugs have been expanded in terms of quantity as results of repetitive researches, but there was no significant change in terms of quality. The reason for these results is that most anti-cancer drugs are applied to cells whose somatic division is vigorous, with a mechanism of stopping cell cycle and inducing apoptosis of cancer cells and this mechanism results in typical side effects such as chemotherapy alopecia, anorexia, and lowered immunity due to leucopenia since the anticancer drugs attack normally dividing cells.
To minimize the side effects of anticancer drugs, targeted cancer drugs have been developed. Up to date, 18 or more of the targeted anticancer drugs have been developed and clinically applied, and more than 200 clinical trials are under investigated. However, these targeted anticancer drugs targeting a specific target have a limit that it may have effect to a cancer expressing the specific target among same type of cancers have a problem that the cancer gets resistance to the targeted anticancer drugs since it should be administrated over a long period of time. In order to compensate this problem, a cocktail therapy combined with prior potent anticancer drugs or a method using a single anticancer drug which attacks multiple targets simultaneously has been used. However, these methods imply risk of causing serious side effects.
Carbon nanotubes have been used in various biomedical fields including imaging and cancer therapy due to their mechanical, optical and chemical properties (Liu, Z. et al., Nano Res., 2:85, 2009; De La Zerda, A. et al., Nat. Nanotechnol., 3(9): 557-62, 2008; Cherukuri, P. et al, J. Am. Chem. Soc., 126(48): 15638-9, 2004; Welsher, K. et al., Nano Lett., 8(2): 586-90, 2008; Zavaleta, C. et al., Nano Lett., 8(9): 2800-5, 2008). Carbon nanotubes as drug delivery materials undergo endocytosis and have been investigated as in vitro drug delivery systems for delivering various biomolecules including anticancer drugs (Liu, Z. et al., ACS Nano., 1(1): 50-6, 2007; Bianco, A. et al., Curr. Opin. Chem. Biol., 9(6): 674-9, 2005), plasmid DNA (Liu, Y. et al., Angew. Chem. Int. Ed., 44: 4782, 2005), and siRNA (small interfering RNA) (Kam, N. W. et al., J. Am. Chem. Soc., 127(36):12492-3, 2005) to cells effectively. Most of previous researches on drug delivery system using carbon nanotubes have been focused to a method for delivering anticancer drugs using single-wall carbon nanotubes to cells. The previous researches used methods for loading anticancer drugs to the single-wall carbon nanotubes using π-π (pi-pi) stacking after coating PEG (polyethylene glycol) on the surface of the single-wall carbon nanotubes (Liu, Y. et al, Angew. Chem. Int. Ed., 48:7668-7672, 2009; Liu, Z. et al, ACS. NANO, 1(1): 50-56, 2007; Liu et al, J. Am. Chem. Soc., 129, 8438-8439, 2007).